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                    Recover捕获异常
            
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                    方法值和方法表达式
            
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                    示例: Bit数组
            
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                    封装
            
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                    接口
            
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                    接口是合约
            
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                    接口类型
            
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                    实现接口的条件
            
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                    flag.Value接口
            
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                    接口值
            
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                    sort.Interface接口
            
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                    http.Handler接口
            
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                    error接口
            
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                    示例: 表达式求值
            
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                    类型断言
            
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                    基于类型断言识别错误类型
            
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                    通过类型断言查询接口
            
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                    类型分支
            
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                    示例: 基于标记的XML解码
            
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                    补充几点
            
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                    Goroutines和Channels
            
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                    Goroutines
            
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                    示例: 并发的Clock服务
            
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        <li class="chapter " data-level="1.9.3" data-path="../ch8/ch8-03.html">
            
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                    示例: 并发的Echo服务
            
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                    Channels
            
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        <li class="chapter " data-level="1.9.5" data-path="../ch8/ch8-05.html">
            
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                    并发的循环
            
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        <li class="chapter " data-level="1.9.6" data-path="../ch8/ch8-06.html">
            
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                    示例: 并发的Web爬虫
            
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                    基于select的多路复用
            
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                    示例: 并发的目录遍历
            
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                    并发的退出
            
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                    示例: 聊天服务
            
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        <li class="chapter " data-level="1.10" data-path="ch9.html">
            
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                    基于共享变量的并发
            
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                    竞争条件
            
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                    sync.Mutex互斥锁
            
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        <li class="chapter " data-level="1.10.3" data-path="ch9-03.html">
            
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                    sync.RWMutex读写锁
            
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                    内存同步
            
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                    sync.Once惰性初始化
            
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        <li class="chapter " data-level="1.10.6" data-path="ch9-06.html">
            
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                    示例: 并发的非阻塞缓存
            
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                    Goroutines和线程
            
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                    包和工具
            
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                    包的匿名导入
            
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                    包和命名
            
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                    工具
            
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                    测试
            
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                <a href="../ch11/ch11-01.html">
            
                    
                    go test
            
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                    测试函数
            
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                    测试覆盖率
            
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                    基准测试
            
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                    剖析
            
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                    示例函数
            
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                    反射
            
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                    为何需要反射?
            
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        <li class="chapter " data-level="1.13.2" data-path="../ch12/ch12-02.html">
            
                <a href="../ch12/ch12-02.html">
            
                    
                    reflect.Type和reflect.Value
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.3" data-path="../ch12/ch12-03.html">
            
                <a href="../ch12/ch12-03.html">
            
                    
                    Display递归打印
            
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        <li class="chapter " data-level="1.13.4" data-path="../ch12/ch12-04.html">
            
                <a href="../ch12/ch12-04.html">
            
                    
                    示例: 编码S表达式
            
                </a>
            

            
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        <li class="chapter " data-level="1.13.5" data-path="../ch12/ch12-05.html">
            
                <a href="../ch12/ch12-05.html">
            
                    
                    通过reflect.Value修改值
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.6" data-path="../ch12/ch12-06.html">
            
                <a href="../ch12/ch12-06.html">
            
                    
                    示例: 解码S表达式
            
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                    获取结构体字段标签
            
                </a>
            

            
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                    显示一个类型的方法集
            
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                    几点忠告
            
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                    底层编程
            
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                    unsafe.Sizeof, Alignof 和 Offsetof
            
                </a>
            

            
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                <a href="../ch13/ch13-02.html">
            
                    
                    unsafe.Pointer
            
                </a>
            

            
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                    示例: 深度相等判断
            
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                                <h2 id="95-synconce&#x60F0;&#x6027;&#x521D;&#x59CB;&#x5316;">9.5. sync.Once&#x60F0;&#x6027;&#x521D;&#x59CB;&#x5316;</h2>
<p>&#x5982;&#x679C;&#x521D;&#x59CB;&#x5316;&#x6210;&#x672C;&#x6BD4;&#x8F83;&#x5927;&#x7684;&#x8BDD;&#xFF0C;&#x90A3;&#x4E48;&#x5C06;&#x521D;&#x59CB;&#x5316;&#x5EF6;&#x8FDF;&#x5230;&#x9700;&#x8981;&#x7684;&#x65F6;&#x5019;&#x518D;&#x53BB;&#x505A;&#x5C31;&#x662F;&#x4E00;&#x4E2A;&#x6BD4;&#x8F83;&#x597D;&#x7684;&#x9009;&#x62E9;&#x3002;&#x5982;&#x679C;&#x5728;&#x7A0B;&#x5E8F;&#x542F;&#x52A8;&#x7684;&#x65F6;&#x5019;&#x5C31;&#x53BB;&#x505A;&#x8FD9;&#x7C7B;&#x521D;&#x59CB;&#x5316;&#x7684;&#x8BDD;&#xFF0C;&#x4F1A;&#x589E;&#x52A0;&#x7A0B;&#x5E8F;&#x7684;&#x542F;&#x52A8;&#x65F6;&#x95F4;&#xFF0C;&#x5E76;&#x4E14;&#x56E0;&#x4E3A;&#x6267;&#x884C;&#x7684;&#x65F6;&#x5019;&#x53EF;&#x80FD;&#x4E5F;&#x5E76;&#x4E0D;&#x9700;&#x8981;&#x8FD9;&#x4E9B;&#x53D8;&#x91CF;&#xFF0C;&#x6240;&#x4EE5;&#x5B9E;&#x9645;&#x4E0A;&#x6709;&#x4E00;&#x4E9B;&#x6D6A;&#x8D39;&#x3002;&#x8BA9;&#x6211;&#x4EEC;&#x6765;&#x770B;&#x5728;&#x672C;&#x7AE0;&#x65E9;&#x4E00;&#x4E9B;&#x65F6;&#x5019;&#x7684;icons&#x53D8;&#x91CF;&#xFF1A;</p>
<pre><code class="lang-go"><span class="hljs-keyword">var</span> icons <span class="hljs-keyword">map</span>[<span class="hljs-keyword">string</span>]image.Image
</code></pre>
<p>&#x8FD9;&#x4E2A;&#x7248;&#x672C;&#x7684;Icon&#x7528;&#x5230;&#x4E86;&#x61D2;&#x521D;&#x59CB;&#x5316;&#xFF08;lazy initialization&#xFF09;&#x3002;</p>
<pre><code class="lang-go"><span class="hljs-keyword">func</span> loadIcons() {
    icons = <span class="hljs-keyword">map</span>[<span class="hljs-keyword">string</span>]image.Image{
        <span class="hljs-string">&quot;spades.png&quot;</span>:   loadIcon(<span class="hljs-string">&quot;spades.png&quot;</span>),
        <span class="hljs-string">&quot;hearts.png&quot;</span>:   loadIcon(<span class="hljs-string">&quot;hearts.png&quot;</span>),
        <span class="hljs-string">&quot;diamonds.png&quot;</span>: loadIcon(<span class="hljs-string">&quot;diamonds.png&quot;</span>),
        <span class="hljs-string">&quot;clubs.png&quot;</span>:    loadIcon(<span class="hljs-string">&quot;clubs.png&quot;</span>),
    }
}

<span class="hljs-comment">// <span class="hljs-doctag">NOTE:</span> not concurrency-safe!</span>
<span class="hljs-keyword">func</span> Icon(name <span class="hljs-keyword">string</span>) image.Image {
    <span class="hljs-keyword">if</span> icons == <span class="hljs-literal">nil</span> {
        loadIcons() <span class="hljs-comment">// one-time initialization</span>
    }
    <span class="hljs-keyword">return</span> icons[name]
}
</code></pre>
<p>&#x5982;&#x679C;&#x4E00;&#x4E2A;&#x53D8;&#x91CF;&#x53EA;&#x88AB;&#x4E00;&#x4E2A;&#x5355;&#x72EC;&#x7684;goroutine&#x6240;&#x8BBF;&#x95EE;&#x7684;&#x8BDD;&#xFF0C;&#x6211;&#x4EEC;&#x53EF;&#x4EE5;&#x4F7F;&#x7528;&#x4E0A;&#x9762;&#x7684;&#x8FD9;&#x79CD;&#x6A21;&#x677F;&#xFF0C;&#x4F46;&#x8FD9;&#x79CD;&#x6A21;&#x677F;&#x5728;Icon&#x88AB;&#x5E76;&#x53D1;&#x8C03;&#x7528;&#x65F6;&#x5E76;&#x4E0D;&#x5B89;&#x5168;&#x3002;&#x5C31;&#x50CF;&#x524D;&#x9762;&#x94F6;&#x884C;&#x7684;&#x90A3;&#x4E2A;Deposit(&#x5B58;&#x6B3E;)&#x51FD;&#x6570;&#x4E00;&#x6837;&#xFF0C;Icon&#x51FD;&#x6570;&#x4E5F;&#x662F;&#x7531;&#x591A;&#x4E2A;&#x6B65;&#x9AA4;&#x7EC4;&#x6210;&#x7684;&#xFF1A;&#x9996;&#x5148;&#x6D4B;&#x8BD5;icons&#x662F;&#x5426;&#x4E3A;&#x7A7A;&#xFF0C;&#x7136;&#x540E;load&#x8FD9;&#x4E9B;icons&#xFF0C;&#x4E4B;&#x540E;&#x5C06;icons&#x66F4;&#x65B0;&#x4E3A;&#x4E00;&#x4E2A;&#x975E;&#x7A7A;&#x7684;&#x503C;&#x3002;&#x76F4;&#x89C9;&#x4F1A;&#x544A;&#x8BC9;&#x6211;&#x4EEC;&#x6700;&#x5DEE;&#x7684;&#x60C5;&#x51B5;&#x662F;loadIcons&#x51FD;&#x6570;&#x88AB;&#x591A;&#x6B21;&#x8BBF;&#x95EE;&#x4F1A;&#x5E26;&#x6765;&#x6570;&#x636E;&#x7ADE;&#x4E89;&#x3002;&#x5F53;&#x7B2C;&#x4E00;&#x4E2A;goroutine&#x5728;&#x5FD9;&#x7740;loading&#x8FD9;&#x4E9B;icons&#x7684;&#x65F6;&#x5019;&#xFF0C;&#x53E6;&#x4E00;&#x4E2A;goroutine&#x8FDB;&#x5165;&#x4E86;Icon&#x51FD;&#x6570;&#xFF0C;&#x53D1;&#x73B0;&#x53D8;&#x91CF;&#x662F;nil&#xFF0C;&#x7136;&#x540E;&#x4E5F;&#x4F1A;&#x8C03;&#x7528;loadIcons&#x51FD;&#x6570;&#x3002;</p>
<p>&#x4E0D;&#x8FC7;&#x8FD9;&#x79CD;&#x76F4;&#x89C9;&#x662F;&#x9519;&#x8BEF;&#x7684;&#x3002;&#xFF08;&#x6211;&#x4EEC;&#x5E0C;&#x671B;&#x4F60;&#x4ECE;&#x73B0;&#x5728;&#x5F00;&#x59CB;&#x80FD;&#x591F;&#x6784;&#x5EFA;&#x81EA;&#x5DF1;&#x5BF9;&#x5E76;&#x53D1;&#x7684;&#x76F4;&#x89C9;&#xFF0C;&#x4E5F;&#x5C31;&#x662F;&#x8BF4;&#x5BF9;&#x5E76;&#x53D1;&#x7684;&#x76F4;&#x89C9;&#x603B;&#x662F;&#x4E0D;&#x80FD;&#x88AB;&#x4FE1;&#x4EFB;&#x7684;&#xFF01;&#xFF09;&#xFF0C;&#x56DE;&#x5FC6;&#x4E00;&#x4E0B;9.4&#x8282;&#x3002;&#x56E0;&#x4E3A;&#x7F3A;&#x5C11;&#x663E;&#x5F0F;&#x7684;&#x540C;&#x6B65;&#xFF0C;&#x7F16;&#x8BD1;&#x5668;&#x548C;CPU&#x662F;&#x53EF;&#x4EE5;&#x968F;&#x610F;&#x5730;&#x53BB;&#x66F4;&#x6539;&#x8BBF;&#x95EE;&#x5185;&#x5B58;&#x7684;&#x6307;&#x4EE4;&#x987A;&#x5E8F;&#xFF0C;&#x4EE5;&#x4EFB;&#x610F;&#x65B9;&#x5F0F;&#xFF0C;&#x53EA;&#x8981;&#x4FDD;&#x8BC1;&#x6BCF;&#x4E00;&#x4E2A;goroutine&#x81EA;&#x5DF1;&#x7684;&#x6267;&#x884C;&#x987A;&#x5E8F;&#x4E00;&#x81F4;&#x3002;&#x5176;&#x4E2D;&#x4E00;&#x79CD;&#x53EF;&#x80FD;loadIcons&#x7684;&#x8BED;&#x53E5;&#x91CD;&#x6392;&#x662F;&#x4E0B;&#x9762;&#x8FD9;&#x6837;&#x3002;&#x5B83;&#x4F1A;&#x5728;&#x586B;&#x5199;icons&#x53D8;&#x91CF;&#x7684;&#x503C;&#x4E4B;&#x524D;&#x5148;&#x7528;&#x4E00;&#x4E2A;&#x7A7A;map&#x6765;&#x521D;&#x59CB;&#x5316;icons&#x53D8;&#x91CF;&#x3002;</p>
<pre><code class="lang-go"><span class="hljs-keyword">func</span> loadIcons() {
    icons = <span class="hljs-built_in">make</span>(<span class="hljs-keyword">map</span>[<span class="hljs-keyword">string</span>]image.Image)
    icons[<span class="hljs-string">&quot;spades.png&quot;</span>] = loadIcon(<span class="hljs-string">&quot;spades.png&quot;</span>)
    icons[<span class="hljs-string">&quot;hearts.png&quot;</span>] = loadIcon(<span class="hljs-string">&quot;hearts.png&quot;</span>)
    icons[<span class="hljs-string">&quot;diamonds.png&quot;</span>] = loadIcon(<span class="hljs-string">&quot;diamonds.png&quot;</span>)
    icons[<span class="hljs-string">&quot;clubs.png&quot;</span>] = loadIcon(<span class="hljs-string">&quot;clubs.png&quot;</span>)
}
</code></pre>
<p>&#x56E0;&#x6B64;&#xFF0C;&#x4E00;&#x4E2A;goroutine&#x5728;&#x68C0;&#x67E5;icons&#x662F;&#x975E;&#x7A7A;&#x65F6;&#xFF0C;&#x4E5F;&#x5E76;&#x4E0D;&#x80FD;&#x5C31;&#x5047;&#x8BBE;&#x8FD9;&#x4E2A;&#x53D8;&#x91CF;&#x7684;&#x521D;&#x59CB;&#x5316;&#x6D41;&#x7A0B;&#x5DF2;&#x7ECF;&#x8D70;&#x5B8C;&#x4E86;&#xFF08;&#x8BD1;&#x6CE8;&#xFF1A;&#x53EF;&#x80FD;&#x53EA;&#x662F;&#x585E;&#x4E86;&#x4E2A;&#x7A7A;map&#xFF0C;&#x91CC;&#x9762;&#x7684;&#x503C;&#x8FD8;&#x6CA1;&#x586B;&#x5B8C;&#xFF0C;&#x4E5F;&#x5C31;&#x662F;&#x8BF4;&#x586B;&#x503C;&#x7684;&#x8BED;&#x53E5;&#x90FD;&#x6CA1;&#x6267;&#x884C;&#x5B8C;&#x5462;&#xFF09;&#x3002;</p>
<p>&#x6700;&#x7B80;&#x5355;&#x4E14;&#x6B63;&#x786E;&#x7684;&#x4FDD;&#x8BC1;&#x6240;&#x6709;goroutine&#x80FD;&#x591F;&#x89C2;&#x5BDF;&#x5230;loadIcons&#x6548;&#x679C;&#x7684;&#x65B9;&#x5F0F;&#xFF0C;&#x662F;&#x7528;&#x4E00;&#x4E2A;mutex&#x6765;&#x540C;&#x6B65;&#x68C0;&#x67E5;&#x3002;</p>
<pre><code class="lang-go"><span class="hljs-keyword">var</span> mu sync.Mutex <span class="hljs-comment">// guards icons</span>
<span class="hljs-keyword">var</span> icons <span class="hljs-keyword">map</span>[<span class="hljs-keyword">string</span>]image.Image

<span class="hljs-comment">// Concurrency-safe.</span>
<span class="hljs-keyword">func</span> Icon(name <span class="hljs-keyword">string</span>) image.Image {
    mu.Lock()
    <span class="hljs-keyword">defer</span> mu.Unlock()
    <span class="hljs-keyword">if</span> icons == <span class="hljs-literal">nil</span> {
        loadIcons()
    }
    <span class="hljs-keyword">return</span> icons[name]
}
</code></pre>
<p>&#x7136;&#x800C;&#x4F7F;&#x7528;&#x4E92;&#x65A5;&#x8BBF;&#x95EE;icons&#x7684;&#x4EE3;&#x4EF7;&#x5C31;&#x662F;&#x6CA1;&#x6709;&#x529E;&#x6CD5;&#x5BF9;&#x8BE5;&#x53D8;&#x91CF;&#x8FDB;&#x884C;&#x5E76;&#x53D1;&#x8BBF;&#x95EE;&#xFF0C;&#x5373;&#x4F7F;&#x53D8;&#x91CF;&#x5DF2;&#x7ECF;&#x88AB;&#x521D;&#x59CB;&#x5316;&#x5B8C;&#x6BD5;&#x4E14;&#x518D;&#x4E5F;&#x4E0D;&#x4F1A;&#x8FDB;&#x884C;&#x53D8;&#x52A8;&#x3002;&#x8FD9;&#x91CC;&#x6211;&#x4EEC;&#x53EF;&#x4EE5;&#x5F15;&#x5165;&#x4E00;&#x4E2A;&#x5141;&#x8BB8;&#x591A;&#x8BFB;&#x7684;&#x9501;&#xFF1A;</p>
<pre><code class="lang-go"><span class="hljs-keyword">var</span> mu sync.RWMutex <span class="hljs-comment">// guards icons</span>
<span class="hljs-keyword">var</span> icons <span class="hljs-keyword">map</span>[<span class="hljs-keyword">string</span>]image.Image
<span class="hljs-comment">// Concurrency-safe.</span>
<span class="hljs-keyword">func</span> Icon(name <span class="hljs-keyword">string</span>) image.Image {
    mu.RLock()
    <span class="hljs-keyword">if</span> icons != <span class="hljs-literal">nil</span> {
        icon := icons[name]
        mu.RUnlock()
        <span class="hljs-keyword">return</span> icon
    }
    mu.RUnlock()

    <span class="hljs-comment">// acquire an exclusive lock</span>
    mu.Lock()
    <span class="hljs-keyword">if</span> icons == <span class="hljs-literal">nil</span> { <span class="hljs-comment">// <span class="hljs-doctag">NOTE:</span> must recheck for nil</span>
        loadIcons()
    }
    icon := icons[name]
    mu.Unlock()
    <span class="hljs-keyword">return</span> icon
}
</code></pre>
<p>&#x4E0A;&#x9762;&#x7684;&#x4EE3;&#x7801;&#x6709;&#x4E24;&#x4E2A;&#x4E34;&#x754C;&#x533A;&#x3002;goroutine&#x9996;&#x5148;&#x4F1A;&#x83B7;&#x53D6;&#x4E00;&#x4E2A;&#x8BFB;&#x9501;&#xFF0C;&#x67E5;&#x8BE2;map&#xFF0C;&#x7136;&#x540E;&#x91CA;&#x653E;&#x9501;&#x3002;&#x5982;&#x679C;&#x6761;&#x76EE;&#x88AB;&#x627E;&#x5230;&#x4E86;&#xFF08;&#x4E00;&#x822C;&#x60C5;&#x51B5;&#x4E0B;&#xFF09;&#xFF0C;&#x90A3;&#x4E48;&#x4F1A;&#x76F4;&#x63A5;&#x8FD4;&#x56DE;&#x3002;&#x5982;&#x679C;&#x6CA1;&#x6709;&#x627E;&#x5230;&#xFF0C;&#x90A3;goroutine&#x4F1A;&#x83B7;&#x53D6;&#x4E00;&#x4E2A;&#x5199;&#x9501;&#x3002;&#x4E0D;&#x91CA;&#x653E;&#x5171;&#x4EAB;&#x9501;&#x7684;&#x8BDD;&#xFF0C;&#x4E5F;&#x6CA1;&#x6709;&#x4EFB;&#x4F55;&#x529E;&#x6CD5;&#x6765;&#x5C06;&#x4E00;&#x4E2A;&#x5171;&#x4EAB;&#x9501;&#x5347;&#x7EA7;&#x4E3A;&#x4E00;&#x4E2A;&#x4E92;&#x65A5;&#x9501;&#xFF0C;&#x6240;&#x4EE5;&#x6211;&#x4EEC;&#x5FC5;&#x987B;&#x91CD;&#x65B0;&#x68C0;&#x67E5;icons&#x53D8;&#x91CF;&#x662F;&#x5426;&#x4E3A;nil&#xFF0C;&#x4EE5;&#x9632;&#x6B62;&#x5728;&#x6267;&#x884C;&#x8FD9;&#x4E00;&#x6BB5;&#x4EE3;&#x7801;&#x7684;&#x65F6;&#x5019;&#xFF0C;icons&#x53D8;&#x91CF;&#x5DF2;&#x7ECF;&#x88AB;&#x5176;&#x5B83;gorouine&#x521D;&#x59CB;&#x5316;&#x8FC7;&#x4E86;&#x3002;</p>
<p>&#x4E0A;&#x9762;&#x7684;&#x6A21;&#x677F;&#x4F7F;&#x6211;&#x4EEC;&#x7684;&#x7A0B;&#x5E8F;&#x80FD;&#x591F;&#x66F4;&#x597D;&#x7684;&#x5E76;&#x53D1;&#xFF0C;&#x4F46;&#x662F;&#x6709;&#x4E00;&#x70B9;&#x592A;&#x590D;&#x6742;&#x4E14;&#x5BB9;&#x6613;&#x51FA;&#x9519;&#x3002;&#x5E78;&#x8FD0;&#x7684;&#x662F;&#xFF0C;sync&#x5305;&#x4E3A;&#x6211;&#x4EEC;&#x63D0;&#x4F9B;&#x4E86;&#x4E00;&#x4E2A;&#x4E13;&#x95E8;&#x7684;&#x65B9;&#x6848;&#x6765;&#x89E3;&#x51B3;&#x8FD9;&#x79CD;&#x4E00;&#x6B21;&#x6027;&#x521D;&#x59CB;&#x5316;&#x7684;&#x95EE;&#x9898;&#xFF1A;sync.Once&#x3002;&#x6982;&#x5FF5;&#x4E0A;&#x6765;&#x8BB2;&#xFF0C;&#x4E00;&#x6B21;&#x6027;&#x7684;&#x521D;&#x59CB;&#x5316;&#x9700;&#x8981;&#x4E00;&#x4E2A;&#x4E92;&#x65A5;&#x91CF;mutex&#x548C;&#x4E00;&#x4E2A;boolean&#x53D8;&#x91CF;&#x6765;&#x8BB0;&#x5F55;&#x521D;&#x59CB;&#x5316;&#x662F;&#x4E0D;&#x662F;&#x5DF2;&#x7ECF;&#x5B8C;&#x6210;&#x4E86;&#xFF1B;&#x4E92;&#x65A5;&#x91CF;&#x7528;&#x6765;&#x4FDD;&#x62A4;boolean&#x53D8;&#x91CF;&#x548C;&#x5BA2;&#x6237;&#x7AEF;&#x6570;&#x636E;&#x7ED3;&#x6784;&#x3002;Do&#x8FD9;&#x4E2A;&#x552F;&#x4E00;&#x7684;&#x65B9;&#x6CD5;&#x9700;&#x8981;&#x63A5;&#x6536;&#x521D;&#x59CB;&#x5316;&#x51FD;&#x6570;&#x4F5C;&#x4E3A;&#x5176;&#x53C2;&#x6570;&#x3002;&#x8BA9;&#x6211;&#x4EEC;&#x7528;sync.Once&#x6765;&#x7B80;&#x5316;&#x524D;&#x9762;&#x7684;Icon&#x51FD;&#x6570;&#x5427;&#xFF1A;</p>
<pre><code class="lang-go"><span class="hljs-keyword">var</span> loadIconsOnce sync.Once
<span class="hljs-keyword">var</span> icons <span class="hljs-keyword">map</span>[<span class="hljs-keyword">string</span>]image.Image
<span class="hljs-comment">// Concurrency-safe.</span>
<span class="hljs-keyword">func</span> Icon(name <span class="hljs-keyword">string</span>) image.Image {
    loadIconsOnce.Do(loadIcons)
    <span class="hljs-keyword">return</span> icons[name]
}
</code></pre>
<p>&#x6BCF;&#x4E00;&#x6B21;&#x5BF9;Do(loadIcons)&#x7684;&#x8C03;&#x7528;&#x90FD;&#x4F1A;&#x9501;&#x5B9A;mutex&#xFF0C;&#x5E76;&#x4F1A;&#x68C0;&#x67E5;boolean&#x53D8;&#x91CF;&#xFF08;&#x8BD1;&#x6CE8;&#xFF1A;Go1.9&#x4E2D;&#x4F1A;&#x5148;&#x5224;&#x65AD;boolean&#x53D8;&#x91CF;&#x662F;&#x5426;&#x4E3A;1(true)&#xFF0C;&#x53EA;&#x6709;&#x4E0D;&#x4E3A;1&#x624D;&#x9501;&#x5B9A;mutex&#xFF0C;&#x4E0D;&#x518D;&#x9700;&#x8981;&#x6BCF;&#x6B21;&#x90FD;&#x9501;&#x5B9A;mutex&#xFF09;&#x3002;&#x5728;&#x7B2C;&#x4E00;&#x6B21;&#x8C03;&#x7528;&#x65F6;&#xFF0C;boolean&#x53D8;&#x91CF;&#x7684;&#x503C;&#x662F;false&#xFF0C;Do&#x4F1A;&#x8C03;&#x7528;loadIcons&#x5E76;&#x4F1A;&#x5C06;boolean&#x53D8;&#x91CF;&#x8BBE;&#x7F6E;&#x4E3A;true&#x3002;&#x968F;&#x540E;&#x7684;&#x8C03;&#x7528;&#x4EC0;&#x4E48;&#x90FD;&#x4E0D;&#x4F1A;&#x505A;&#xFF0C;&#x4F46;&#x662F;mutex&#x540C;&#x6B65;&#x4F1A;&#x4FDD;&#x8BC1;loadIcons&#x5BF9;&#x5185;&#x5B58;&#xFF08;&#x8FD9;&#x91CC;&#x5176;&#x5B9E;&#x5C31;&#x662F;&#x6307;icons&#x53D8;&#x91CF;&#x5566;&#xFF09;&#x4EA7;&#x751F;&#x7684;&#x6548;&#x679C;&#x80FD;&#x591F;&#x5BF9;&#x6240;&#x6709;goroutine&#x53EF;&#x89C1;&#x3002;&#x7528;&#x8FD9;&#x79CD;&#x65B9;&#x5F0F;&#x6765;&#x4F7F;&#x7528;sync.Once&#x7684;&#x8BDD;&#xFF0C;&#x6211;&#x4EEC;&#x80FD;&#x591F;&#x907F;&#x514D;&#x5728;&#x53D8;&#x91CF;&#x88AB;&#x6784;&#x5EFA;&#x5B8C;&#x6210;&#x4E4B;&#x524D;&#x548C;&#x5176;&#x5B83;goroutine&#x5171;&#x4EAB;&#x8BE5;&#x53D8;&#x91CF;&#x3002;</p>
<p><strong>&#x7EC3;&#x4E60; 9.2&#xFF1A;</strong> &#x91CD;&#x5199;2.6.2&#x8282;&#x4E2D;&#x7684;PopCount&#x7684;&#x4F8B;&#x5B50;&#xFF0C;&#x4F7F;&#x7528;sync.Once&#xFF0C;&#x53EA;&#x5728;&#x7B2C;&#x4E00;&#x6B21;&#x9700;&#x8981;&#x7528;&#x5230;&#x7684;&#x65F6;&#x5019;&#x8FDB;&#x884C;&#x521D;&#x59CB;&#x5316;&#x3002;&#xFF08;&#x867D;&#x7136;&#x5B9E;&#x9645;&#x4E0A;&#xFF0C;&#x5BF9;PopCount&#x8FD9;&#x6837;&#x5F88;&#x5C0F;&#x4E14;&#x9AD8;&#x5EA6;&#x4F18;&#x5316;&#x7684;&#x51FD;&#x6570;&#x8FDB;&#x884C;&#x540C;&#x6B65;&#x53EF;&#x80FD;&#x4EE3;&#x4EF7;&#x6CA1;&#x6CD5;&#x63A5;&#x53D7;&#x3002;&#xFF09;</p>

                                
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